Self-Diffusion and Nuclear Relaxation inHe3

Direct spin-echo measurements of diffusion coefficient ($D$) and spin relaxation time ($T_1$ and $T_2$) have been performed on ${\mathrm{He}}^3$, with an accuracy ∼2% in the range 0.5°K to 4.2°K and at pressures to 67 atmos in the liquid, the solid, and in dilute solutions of ${\mathrm{He}}^3$ in ${\mathrm{He}}^4$. Unactivated diffusion is observed to the lowest temperatures in the liquid, but not in the solid. By measurement of $D$ at 19 atmos we find an activation energy of 13.7°K for the production of scatterers in He II. There is an extended discussion of experimental details.